不同食用植物油氧化稳定性的研究

采用油脂氧化稳定性测定仪,通过测定采集自中国市场上的48个不合抗氧化剂的小包装植物油样品的诱导时间,比较分析不同食用植物油的氧化稳定性差异.结果表明,植物油稳定性从优到劣的排序为:芝麻油、橄榄油、三四级菜籽油、玉米油、一级菜籽油、花生油、大豆油、一级葵花籽油、茶籽油、三级葵花籽油、亚麻籽油.实验结果说明植物油中的微量抗氧化物质是影响植物油氧化稳定性的主要因素.     

超高压均质提高豌豆蛋白稳定的乳状液的物理和氧化稳定性

采用常规均化(CH,15 MPa)和超高压均化(UHPH,100～300 MPa)处理豌豆蛋白稳定的乳状液,对其物理和氧化稳定性进行评价。结果表明:与CH处理相比,在100 MPa和200 MPa的超高压处理下,乳状液的乳化活性和乳化稳定性较好,产生的乳化液滴粒径较小,乳状液对乳脂和氧化反应具有很高的稳定性。但是,相比于100 MPa和200 MPa乳状液,300 MPa处理的乳状液粒径更大值,并且乳化性能有所下降,界面上的蛋白含量有所降低。因此,控制超高压均质的压力在200 MPa以下时,超高压均质能够提高乳状液的物理和氧化稳定性。     

不同蛋白对水包油型乳状液稳定性影响

以乳清分离蛋白和大豆分离蛋白为乳化剂,选用紫苏油、橄榄油、玉米油作为油相制备水包油(O/W)型乳状液。研究2种蛋白对不同乳状液的物理特性及稳定性的影响,其物理特性包括粒径、ζ-电势、界面蛋白含量,稳定性则包括储存稳定性和氧化稳定性。结果表明,不同蛋白对乳状液特性的影响较大,以乳清分离蛋白作为乳化剂时,乳状液体积平均粒径(D4,3)较小,ζ-电势绝对值较大(又以紫苏油乳状液最大,其D4,3为1.4μm,ζ-电势为-25.6 m V),界面蛋白含量较高,体系稳定性优于添加大豆分离蛋白的乳状液。在同一乳化剂作用下,橄榄油乳状液的氧化稳定性较其他2种植物油所得体系更好。     

4种植物油室温氧化过程中自由基变化分析

为探明植物油室温氧化过程中自由基的变化,以亚麻籽油、花生油、葵花籽油和油茶籽油4种植物油作为研究对象,利用电子顺磁共振和核磁共振技术研究自由基及氢谱的变化情况。结果表明:亚麻籽油、葵花籽油和花生油在室温氧化过程中主要产生烷基自由基(R·)、烷氧自由基(RO·)、烷过氧自由基(ROO·)以及其它未知自由基(DMPO-X),其含量各有不同。亚麻籽油和花生油中各自由基含量排序为DMPO-X＞RO·＞R·＞ROO·,葵花籽油中各自由基含量排序为RO·＞DMPO-X＞R·＞ROO·。茶籽油在室温氧化过程中主要产生3种自由基,其含量排序为RO·＞DMPO-X＞ROO·。4种植物油的1H NMR谱的化学位移无明显变化,其氧化前、后各特征峰峰面积发生变化,二级氧化产物的特征峰未检测到,4种植物油处于氧化初级阶段。以亚麻酸为主或以亚油酸和油酸为主的植物油在室温氧化过程中主要产生DMPO-X;以亚油酸或以油酸为主的植物油在室温氧化过程中主要产生RO·。     

不同植物油水包油型乳状液物理特性及氧化稳定性研究

以紫苏油、橄榄油、棕榈油和葵花籽油为油相,以乳清分离蛋白为乳化剂,制备水包油(O/W)型乳状液,研究其粒径、ζ-电位、絮凝指数等物理特性,比较不同乳状液在贮存期间的氧化稳定性。结果显示,4种乳状液中,紫苏油乳状液体积平均粒径D_(4,3)较小(0.824μm),ζ-电位绝对值较大(37.5mV),呈现良好的物理贮存稳定性;但由于油脂中有较高的多不饱和脂肪酸,体系易被氧化。棕榈油乳状液具有良好的氧化稳定性,体系初级和次级氧化产物浓度均最低;但乳状液粒径较大(D_(4,3)为1.845μm),物理稳定性较差。通过内源性荧光测定发现,乳状液中蛋白质氧化与脂质氧化存在一定关联性。     

不同脂肪酸组成的植物油氧化稳定性的研究

通过气相色谱法分析了菜籽油、大豆油、花生油、葵花籽油、山茶油、调和油、玉米油和芝麻油这八种天然食用植物油的脂肪酸组成,采用Schall烘箱法,以过氧化值(POV)和脂肪酸组成为参考指标,研究了加热加速氧化对不同植物油氧化稳定性的影响。并运用Matlab数学工具建立模型,探讨POV值与脂肪酸组成之间的关系。结果表明:温度对各种植物油的氧化过程影响显著,加速氧化过程中,脂肪酸总体变化很小,多不饱和脂肪酸(PUFA)减少,饱和脂肪酸(SFA)和单不饱和脂肪酸(MUFA)有不同程度的增多,n-3比n-6系列多不饱和脂肪酸更易氧化减少。氧化稳定性由强到弱依次为花生油、山茶油、芝麻油、菜籽油、玉米油、调和油、大豆油、葵花籽油。初步建立起了以PUFA含量分类,加速氧化条件下过氧化值与脂肪酸组成之间的关系模型。     

葵花籽蛋白水解物对水包油型乳状液物理和氧化稳定性的影响

利用碱性蛋白酶对葵花籽蛋白进行适度水解后,将葵花籽蛋白水解物(SSH)添加到以单甘酯作为乳化剂制备的乳状液中,通过测定乳状液的乳化活性、乳化稳定性、粒径、絮凝指数、凝结指数以及乳状液贮藏14 d过氧化值和丙二醛含量的变化,评价SSH对乳状液物理和氧化稳定性的影响。结果表明:添加SSH可显著提高乳状液的乳化活性、乳化稳定性、絮凝和凝结稳定性,显著降低乳状液的粒径;SSH添加量为1.0%时,乳状液具有较好的物理稳定性,同时又具有较好的氧化稳定性。     

不同植物油预乳化液对乳化羊肉肠品质的影响

以乳化羊肉肠为研究对象,以添加羊尾油的乳化羊肉肠作对照组,分别用预乳化后的大豆油、菜籽油、葵花籽油或杏仁油乳化液替代75%的羊尾油作处理组,考察不同植物油预乳化液替代动物脂肪对乳化羊肉肠的蒸煮损失、色泽、质构和微观结构等性质的影响。结果表明：植物油预乳化液替代脂肪不仅可以降低乳化羊肉肠的脂肪添加量（p<0.05）,还可显著增加羊肉肠的水分含量和蛋白质含量（p<0.05）;在蒸煮损失方面,葵花籽油组和杏仁油组最低,对照组最高;大豆油组、菜籽油组、葵花籽油组、杏仁油组持水性比对照组分别增加了0.47%、0.44%、0.54%、0.31%;与对照组相比,大豆油组、葵花籽油组硬度、咀嚼性显著增加（p<0.05）,菜籽油组、葵花籽油组、杏仁油组弹性显著增加（p<0.05）。微观结构上,对照组整体多呈团簇状,经植物油预乳化液替代后可赋予肠体立体的凝胶网络结构,尤其葵花籽油组网络线条更加致密,孔隙较小且分布较为均匀。     

磁珠提取DNA结合PCR-HRM方法鉴定植物油掺伪

为有效鉴别精炼植物油掺伪，通过先富集油中核酸，然后在水相溶液中加入磁珠和特定吸附液来吸附脱氧核糖核酸(DNA),实现快速高效的磁珠DNA提取，并结合荧光定量聚合酶链式反应(PCR)扩增高拷贝叶绿体基因rbcL,对产物进行高分辨率熔解曲线(HRM)分析，获得菜籽油、大豆油、花生油、玉米油、葵花籽油、芝麻油、亚麻籽油、山茶油、稻米油和棉籽油HRM的特征曲线。通过对不同货架期的精炼大豆油和花生油掺伪样品的真实性验证，表明建立的方法可有效解决精炼植物油中掺杂其他植物油的鉴别难题。     

基于甘三酯指纹图谱及化学计量学的青海亚麻籽油掺假识别研究

采用HPLC-RID测定青海省亚麻籽油甘三酯组成,并利用指纹图谱相似度评价系统及判别分析对亚麻籽油进行掺伪识别分析。结果表明,亚麻籽油中共检测出8种甘三酯,其中主要甘三酯为OLnLn(22.82%)、LnLnLn(20.40%)、OLnO(14.81%)、OLLn(13.59%);运用指纹图谱相似度评价系统构建亚麻籽油甘三酯标准指纹图谱以鉴定亚麻籽油中掺入菜籽油、大豆油、花生油、葵花籽油、玉米油、芝麻油(10%、20%、30%、40%、50%)的掺伪样品,当掺入植物油质量分数达10%以上时,可以准确判别纯亚麻籽油和掺伪亚麻籽油。为进一步识别亚麻籽油中掺假的植物油种类,对掺伪油样进行判别分析,建立的判别模型适用于亚麻籽油中掺入大豆油质量分数大于10%、掺入菜籽油、花生油、葵花籽油、玉米油、芝麻油浓度大于20%时的掺伪油种类的识别鉴定。     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

Detection of adulteration of locust bean gum with guar gum by capillary electrophoresis and polarized light microscopy

Capillary electrophoresis (CE) and polarized light microscopy (PLM) were utilized in the detection of the adulteration of locust bean gum with guar gum. For CE analyses, standards of locust bean and guar gums were extracted with 30% CH₃CN, removing the residual proteins from the gum matrix. A 8.75 mM NaH₂PO₄-20.6 mM Na₂B₄O₇ buffer, pH 9, was used to separate these proteins and to identify marker proteins that were present in the guar gum. These markers did not co-migrate with components in the extracts of mechanically processed locust bean gum, and are used as indicators of adulteration. Using PLM with toluidine blue and iodine staining techniques, unadulterated locust bean gum samples were distinguished from mixed samples through the differential staining of components in locust bean versus guar and tara gums. These experiments in the use of CE and PLM provide orthogonal and complementary methods for the verification of 'true' positives and the elimination of 'false' positives.